--- a/src/samples.cpp
+++ b/src/samples.cpp
@@ -75,7 +75,7 @@ struct sampleChannel
 sampleChannel ch4, ch5;
 
 
-const sbyte galwayNoiseTab1[16] =
+const ubyte galwayNoiseTab1[16] =
 {
 	0x80,0x91,0xa2,0xb3,0xc4,0xd5,0xe6,0xf7,
 	0x08,0x19,0x2a,0x3b,0x4c,0x5d,0x6e,0x7f
@@ -84,7 +84,7 @@ const sbyte galwayNoiseTab1[16] =
 ubyte galwayNoiseVolTab[16];
 sbyte galwayNoiseSamTab[16];
 
-const sbyte sampleConvertTab[16] =
+const ubyte sampleConvertTab[16] =
 {
 //  0x81,0x99,0xaa,0xbb,0xcc,0xdd,0xee,0xff,
 //  0x00,0x11,0x22,0x33,0x44,0x55,0x66,0x7f
